Indian Ocean, hydrographic survey for WOCE Hydrographic Program, Line I9N. The basic hydrogrpahy program consisted of salinity, dissolved oxygen and nutrient (nitrite/nitrate, phosphate and silicate) measurements made from bottles taken on CTD/rosette casts, plus pressure, temperature, salinity and dissolved oxygen from CTD profiles. 130 CTD/36 bottle rosette casts, usually to within 5 metres of the bottom. Water samples were analysed for nutrients, CFC, tritium/helium, CO2, 14C. ADCP, underway meterological and sea surface temperature and salinity were also logged and a series of floats and drifters were also deployed.